The Mutant TMNT X OC Fanfiction
by beetroot206
Summary: When Nerio was young her parents were murdered and she was taken and experimented on by a man called Bishop. After years she finally saw her opportunity and escaped, but she's not the same now she's are half mutant half human. In her mission to get revenge on Bishop Nerio finds something that could change the world but does she have the power to stop it alone?
1. Chapter 1

So sorry to disappoint all of you, and not continuing the fanfiction, the support was great, but it just wasn't really my thing I guess. I was looking through my old notes and I found a TMNT Fanfiction outline I wrote about the same time I did this fanfic, but I never published or finished it, so I've decided to make a new fanfiction using some of the ideas from the outline. If you're interested I'll probably be starting in the next week or so. Here's the backstory for it, hope you enjoy!

"To most people you're just a normal girl, but when you were young your parents were killed and you were taken and experimented on by a man called Bishop. (Yeah you're not very happy about that) After years you finally saw your opportunity and escaped, but you're not the same. No, you're not particularly traumatized, but you are half mutant half human due to the experimentation. After you escaped you didn't wanna go to some foster home so you live by yourself in an old warehouse(yes pretty cliche I know). And no you're not vigilante or anything, you don't care much about the rest of the world, they can take care of themselves and if they can't that's nothing to do with you. If anything most people would see you as a bit of a villain because you steal, although it's only in order to survive, and that's your back story. Your name is Nerio.

Tell me your thoughts, hope you liked it :3 And maybe you can help me pick a title for the book!


	2. Chapter Two: More Mutants?

**Nerio POV**

I'm just out jumping from rooftops, getting some air when I see four strange figures doing the same not too far away from me. They're clearly not human so now I'm pretty curious. Should I get a closer look? Maybe they might see me... Oh who cares I can take care of myself, I are a mutant after all, well half mutant anyways what's the worst that could happen? Famous last words...after arguing with myself for some time I decide to follow them before they're out of sight completely with all that time I just wasted.

After following them for a few minutes I hear a scream, I look down at the streets and see a woman being robbed by Purple Dragon thugs. Honestly who cares? She's stupid for going out in this neighbourhood at night alone, and defenseless! Well, those four whatever they are seem to care, because they rush to help her, probably vigilantes of some sort.

As they are occupied fighting the attackers I run to the closest cover, which happens to be a garbage can to watch from, I don't want them to see me obviously. Since they're not clearly not human as they were jumping from rooftops, I want to know more. My guess is they're like me, a mutant, only probably farther mutated than I am, because now that I see them clearer...they're...turtles? That's a first Crime fighting walking mutant turtles? While I were lost in thought they had left without a trace. I really need to stop getting distracted so easily at key moments.

I need to find them again...I need revenge on Bishop for killing my parents, and if he turned me half mutant he might have done the same to them. If they know of him even that can help me track him down, whether they're allies, enemies, or what if can help. I don't exactly know if these turtles will be willing to help me so I need to find out who or what they are and what they know about Bishop, if anything. I will avenge your parents and Bishop will die.


	3. Chapter Three

**Leonardo POV**

 _Earlier on patrol, I thought I saw someone following us, although I can't be sure I should we should probably head back to the lair, Raph isn't going to be too happy about that, but if someone was following us it's best we head back. Not looking forward to this one.._

"Um, guys I think we should be heading back now," I said expecting a big argument as usual.

"FINALLY IS FREEEEEEZING OUT HERE!" _Mikey being overdramatic as usual, but much to my surprise no one else complained. Well, that's a first not even any questions! Wow, it's nice actually having them not question me, the LEADER's orders for once. Guess it really is cold_.

And with that, we headed back to the lair. I think the person following us from earlier has stopped, or maybe they were never there hopefully so.

 **Time Skip: Next Night**

 **Nerio POV**

 _Finding their base or wherever those turtles hide during the day(they obviously can't come out during the day or it would be all over the news) would be a good place to start. Not exactly sure what I'd be looking for there, but even just knowing more about them will help, even if I can't find anything about Bishop there._

Here's the plan: search the city until I find them pretty much when/if I can find them I will place this tracker I've been working on all day on one of them however you're going to do that. I may have to fight them to get it on unnoticed. When it comes daytime they should be wherever the stay by then so I will know the location for the following night when they leave assuming they go out jumping around rooftops saving silly woman for Purple Dragons every night.

Ipack a small bag containing the tracker, a few smoke bombs, which took an eternity to make, and some night vision goggles, hey you never know what could happen!

I then left the warehouse I lived in and headed for the closest tall building. I didn't really feel like breaking in so you extend your claws and start climbing up the side of the building. As I were climbing up an office worker turned to look out the window in reaction I slipped and fell a few floors and then got my grip back with one hand and then pulled myself back up.

 _Hope they didn't see me, not that it really matters, to be hones_ t.

Rather quickly I get to the top and start jumping from rooftops. It is necessary because I would be seen by just about everyone if I walked on the streets, but you enjoyed feeling the cold air on my face anyway.

After about 30 minutes of leaping off buildings and latching onto new ones, I saw those four turtles fighting things on another roof. This was the chance I needed to find the opportune moment to place a tracker on one of the four.

I got closer and hide behind a large air vent on the same building. Okay, they were actually nearly done fighting so I would make your move soon, they were distracted fighting, but it would be difficult to get close while they were fighting so I decided to try and throw it one just before they left after they were done. Speaking of all the Kraang bots, it seems that's who they were fighting are all defeated so now's the time.

Just as I'm about to come out from my cover something terrible happens...you...fart, like really loud.

 _Well, my cover's blown, I would laugh if this wasn't a dangerous situation..._

 _"_ Mikey!"They all said at the same time looking pretty at the orange turtle, I'm gonna assume he's the silly one then and I now know he's called Mikey, interesting.

"Hey, it wasn't me!"

"We all know it was Mikey."The one in blue rolled his eyes.

"Who cares let's just go!"The red-clad turtle moaned.

"Seriously it wasn't actually me..."

 _I had no idea these guys would be so immature! I need some popcorn!_

Finally, you I bored of them arguing over my stupid fart...yes I can't believe I actually farted on this serious occasion, so I came out from my hiding spot and too embarrassed to try and explain myself I decided to fight them and place a tracker on one would be the easiest way to settle things.

I extend my claws and tail ready to fight when they realize I'm about to attack they run at me weapons at the ready, weren't exactly expecting that so soon, but okay let's fight.


	4. Chapter Four: First Fight

**Nerio POV**

When they start running in my direction I quickly swipe all their legs with my tail knocking them all over. They quickly recover and come running at me again.. _wow great tactics guys._ This time I jump behind them, quickly kicking Mikey and the purple-clad turtle from behind making them both fall over.

 _I was expecting quicker reactions than that, this will be easier than I thought._

The other two turtles were faster and quickly turned around and start to attack, but I quickly use my claws to block them both. Then I pull my first trick and swipe both their legs again since they all have a weakness for that or maybe my tail's just really strong which is probably the case. Then all the turtles get back on their feet, finally understanding not to charge at me again they get in their stances, ready for me to attack.

 _Like who's attacking is going to change if they win of not now I'm sure I'll win either way._

I run towards them as fast as I can swiftly dodging all their attacks then I kick Mikey in the plastron sending him into the large vent I had previously hidden behind, a little harder than I meant to. (I didn't want to seriously hurt any of them after all this was all just a distraction to place the tracker). Next I front roll between the remaining standing turtles and grab the end of the bo staff one of the turtles is using for a weapon fling him into the air, spinning around while he's still grabbing it knocking over all the turtles again.

*giggles* _they must be tired of being knocked over by now._

Then when they're all knocked down I quickly throw the tracker on Mikey before anyone has time to get up without them noticing.

Then I walk over to near the edge of the building ready to leap to another building while the turtles are getting up when one of them speaks.

"Who are you?" The blue-clad turtle asks wearily. (probably because I just beat them all up, oops)

You turn your head and smirk, "The name's Nerio." and with that, I use your one of your smoke bombs and escape.

 _Well, that was surprisingly easy._


	5. Chapter 5: Is ThAt A bAgEl?

**Nerio POV**

(The following day) This is perfect! Now I know exactly where their base is! To be honest, I were expecting more from them, being mutants and all. I should never underestimate your enemy, but it was pretty hard right now. All the easier for I though.

I got the GPS tracker out of my bag and set it on a table, along with the rest of the things from my bag. I needed to get a few things for tonight's fun.

-A sketchbook (for sketching the layout of wherever they stay)

-Some smoke bombs

-A simple flashlight (you never know it could be dark there)

-And finally, a wrist gun loaded with tranq's you tweaked a few days ago.

-A few USBs

Now that I have everything I only have to wait now...I may as well go around town a bit have a look around, maybe steal some stuff to pass the time.

Iwere just walking around the streets when I come to a bakery, I'm pretty hungry may as well steal a bagel or something. It seems closed, all the better for me, less likely to get caught that way. I smash the window with my fist and steal bagel on your way out suddenly someone speaks scaring the life out of me making me jump.

"Is that a bAgel?" a homeless girl on the street asks with a strong American accent.

"Huh? What do you want?" I say regaining your composure quickly, rather embarrassed a homeless girl just scared the life out of me.

"Your bagel. Now."

Before I reply a thought comes into my head...I could use a chairwoman, and I bet this girl would be willing, as long as I give her that bagel. Honestly, it doesn't matter that she probably has no qualifications in anything to do with computers, I can show her what she needs to do when I'm on my missions. I know telling you where to go and stuff.

"Hey, what's your name?"

"Bethany."

"How would you like a job?"

"What kinda of jab?" she said suspicious but curious.

"The illegal kind that gets you bagels and somewhere to live."

"I'm listeeenin'."

"How do we say this, I need a woman in the chair and you might do if you're willing, and yes I know this is pretty...well really really random, but I have a feeling you'll be perfect for the job."

"Well, little miss prophet from above, I happen to be an excellent hacker," Bethany replied smugly.

"So...you in?"

"You mean you want me to go live with a random girl who just broke into a bakery in front of me who is offering me bagels to work for her? YAAS DUH!"

"Wait seriously?"

"Mhmmmmmm."

"Wow, okay, come with me we got some work to do."

"I don't like work..."

"What was that?"

"Oh, nothin'."


	6. Chapter 6

Chapter 6

Nerio POV

After walking through the DISTGUSTANG sewer for way too long I come to the turtles' lair entrance. _Seriously there's like no security hear I can literally walk right in! What's with superhero's having no security at the base of their operations?_

I go in and start having a look around to see what's here and if I can find anything useful. It's not exactly what I expected...it's not like I had thought about it much, but for starters, I was at least expecting a door! I then hear a loud slurping in my ear.

"Hey, Bethany is that you?!" I speak into my comm talking to Bethany now my 'woman in the chair' as it were.

"Huh? What? Yeah. No. Maybe. I don't know."

"Seriously unless you have something to say keep quiet, would ya?"

"Technically I wasn't actually speaking just drinking my third can of this delicious soda I found in your fridge."

"YOU WHAT?"

"Huh?"

"Ugh nevermind we'll talk about this later in case you didn't notice I'm a little preoccupied."

"How?"

"I don't know maybe I'm sneaking into a bunch of mutants base!"

"It doesn't even have a door so I only had to disable a few cameras so I don't think it takes that much effort to go in look around and get the blueprints."

"Whatever just keep quiet."

I walk around each room getting a basic idea of the layout drawing a rough sketch on my notepad of the rooms tripping over various empty pizza boxes in the process.

(I know it's pretty detailed but you can imagine it otherwise)

I see a messy desk with a computer on it so maybe I can get some information from it. I quickly turn it on and plug in a USB downloading all the files. Then I hear a noise coming from one of the rooms.

"I thought there wouldn't be anyone in here."

"What is there someone in there?"

"I don't know, but I heard a noise, I'm gonna check it out now."

"I didn't know you were into ghosts."

"Seriously just keep quiet unless spoken to."

"But you did speak to me."

"UGH just keep quiet!"

With that, I snooped into a room with a large tree in the centre (which is kind of weird) and a few weapon racks around the place, presumably the dojo. There was a door at the end of it, probably where the noise was coming from, so I very slowly and quietly slide it open revealing a giant sleeping rat! In shock, I take a few steps back tripping over a fallen branch from the tree with a thud. _Oh, I hope I didn't wake that thing up!_

"Quiet Mikey." the rat says and turns over to sleep again.

 _Mikey must be the clumsy one then...that was too close, time to get out of here! Although first I should get some DNA samples from the turtles to confirm they are mutants and not some other strange creatures._

There are four bedrooms each with a name above the door, Leonardo, Raphael, Donatello, and Michelangelo. Since they're all the same to me I enter the closest one, Mikey's room. It's a huge mess, to be honest, and it stinks!

"Eww, this room stinks!"

"Just hurry up I'm bored."

"Whatever...you're not even here anyway."

I get a little cotton swab out of your bag and swipe one the empty pizza boxes and then put it away in my bag.

"Alright all done I'm on my way back now."

"FINALLY!"

"I haven't even been away that...long..."

"What?"

"Uh oh."

"I don't like repeating myself, WHAT?"

"They're back!"

Sorry, I haven't updated in a while, I've been busy (not really I'm just lazy) doing things in the holidays (getting fat on the sofa watching TV in other words) See ya!


	7. Chapter Seven

_Chapter Seven  
_

_Oh no, what on earth am I suppose to do now? Think Nerio think... I can't just wait around here!_

Just then I hear some shouting coming from a few rooms away. _Sounds like they're arguing or something._ Then footsteps getting louder and closer to the room I'm in!

I look quickly around the room for something to hide behind or another way out or something when I see a large pipe going along the centre of the room. Just as the door starts to open I jump up and grab the pipe just above the door and hope I'm not spotted.

The turtle (presumably Mikey) enters the room heading straight for the bed plopping down onto it face first with a groan.

 _Well, he seems tired. Good then he won't notice me so easy, now's my chance!_

As silently as I can you I to the floor and tiptoe out of the room and look around for any sign of the other turtles. I don't see anyone in the main room so you silently walk through towards the exit.

"Hey!"

"Shoot!" I hear Mikey running up behind you (I could tell from his voice) so I run as fast as I can out of the lair and through the sewers to the surface. He didn't catch me, as I am very fast being having extra speed than a normal person (or mutant).

After I'm sure I'm not being followed I slow down a bit to enjoy the NYC view.

"Mission complete on my way back now." I speak into me comm to Bethany whom I completely forgot about during my escape.

"Sure took you long enough."

"I didn't even take that long." I mumble

"W-w-waaaait hold on you mean you're coming back now?"

"Well, that's what I just said isn't it genius?"

"Like right now?"

"Yes, Bethany like right now."

"ugh oh.."

"What did you do?.."

"Um, nothing I gotta go..."

"W-wait what?" But she had already turned her comm off. "Drat!"

 _What has she done now? I better get back quickly if I want to find out._

 **Time Skip: 20 minutes later**

I finally arrive back and as you enter the warehouse I'm greeted by an awful sight..

Bethany sitting in the midst of empty pizza boxes, sodas, and literally every other food I can think of all over the floor, as she drops the can she was putting in the bin(presumably trying to tidy up) with a nervous chuckle."

"It wasn't me! It was...the..."

"The what? What do you have to say for yourself."

"The um...the cat...yes the cat."

"We don't have a cat."

"Well...um...are you accusing me of lying?"

"Yes, I am as a matter a fact! Now, what is all the mess?!"

"Well, we got sodas, pizza boxes, chip bags-"

"Yes I know what it is, but why is it all over the floor?!"

"Um...reasons..."

"Okay, I think we need to set some boundaries here!"

"Yes, I agree!"

"Huh?" I asked confused.

She grabs some paint and a brush and paints it around my feet in a small circle.

"That'll do."

"What's this?"

"Boundaries." Bethany replies simply.

*facepalm* "I'm going to bed"

"Yeah me too, sleep does sound pretty appealing."

"No I'M going to bed, YOU'RE cleaning up this mess!"

"Fiiine."

As I'm walking to your room I stop and say," Wait a minute...how did you get all the food anyway?"

"Oh, I found some money in the cabinet."

"You mean my highly protected safe?!"

"Yeah, that."

"YOU- you know what, nevermind I've had enough for one day we can sort this out tomorrow I'm going to bed."

Thanks for reading!

I've been updating more recently although sorry if I stop for awhile, because since this fanfiction is available on other platforms that allow it to be the reader I write it in the reader's pov so when I'm updating on I have to go through it all and change a lot of the wording.


	8. Chapter 8

**Mikey POV (Just so you don't get confused this is just after Nerio escaped the lair in Mikey's POV)**

 _Ahh, she's so fast! How's that even possible? I've been running for like two whole minutes already! I'm never gonna catch her in like a bazillion years! I should go back to the lair and tell the others._

 **Time Skip: Two Minutes Later** _ **(because I'm lazy)**_

 _ **(M = Mikey**_

 _ **L = Leo**_

 _ **R= Raph**_

 _ **D = Donny**_

 _ **N = Nerio**_

 _ **B = Bethany)**_

M: "GUYS!" I say bursting into the lair.

L: "What now Mikey?"

M: "It's Nerio, I caught her in the lair and chased her out, but she was way to fast so I came back here to tell you guys! How'd she get in here? How does she know where the lair is? Why was she here? Maybe she came to steal the pizza! GUYS HAS ANYONE CHECKED WHERE THE PIZZA IS?!" Mikeys says in one big mouthful.

L: "W-w-wait slow down, what?"

M: " I said, Nerio was in the lair and I chased her out, and I was thinking maybe she came to steal our pizza, what if-"

R: "What?! You mean Nerio broke into the lair?!"

M: "Yeah I'm pretty sure that's what I just said, wait that is what I said right?"

L: "Hey, Mikey what's that on your shell?"

M: "What? There's something on my shell? Really? What? Where is it? Get it off! Get it off meeee!" Mikey screams going round in circles trying to touch the back of his shell.

Donny comes over and lifts a very small electronic device off Mikey's shell and examines it closely.

P: "It seems to be some kind of micro tracker."

L: "That's how she knew where the lair was! Mikey how did she get that on you without you noticing? We're supposed to be ninjas."

R: "Yeah we are, but Mikey? No surprise she got it on him, I bet it's been there for days!"

M: "Hey!"

R: "What?"

D: "Um... you two keep arguing I'm going to go see if there fingerprints or anything on this thing."

 **Time Skip: The Next Day**

 **Nerio POV**

I grouchily coming out of my room to the main room where I see Bethany on a laptop, in a surprisingly tidy room.

N: "Oh you actually tidied up."

B: "Yeah..."

I eye her suspiciously and ask, "So what are you doing anyways?"

B: "Oh I was just looking through the USB you brought back from the turtles' lair. Matter 'o fact I just finished looking through it."

N: "And?"

B: " I finished talkin'."

N: *sigh* "I mean was there anything useful on it?"

B: "Ye."

N: "Well, what was it?"

B: "There was a file about their mutation, Lord knows why, but it said something about a vile of mutagen smashed and got into their systems, by accident. Here's the useful part, the vile said T.C.R.I. on it."

N: "Kraang... I should've known."

B: "Huh?"

N: " T.C.R.I. stands for Techno Cosmic Research Industries it's some kind of scientific corporation. I don't really know what goes on in there, but I do know it's run by the Kraang."

B: " Oh... don't really understand anything you just said, but what do they have to do with anythin'?"

N: " I never really thought about it before, but now that I come to think of it...they could very well be the ones responsible for experimenting on me!"

B: "You were experimented on?"

N: " Oh, yeah I didn't tell you. My parents were both murdered and I was taken and experimented on when I was young, by a man called Bishop, and that's all I know. How do you think I'm a mutant?"

B: " You're a mutant?"

N: *laughs* "You didn't figure that one out? Yes, I'm a mutant, well half mutant. Anyway back to the point I was to avenge my parents obviously so I'm going to track down Bishop and make him pay, and he might be with this Kraang group."

B: " Okay that's all pretty cool, so what's da plan y'all?"

N: "Break into T.C.R.I."

B: "You really like breakin' into places don't ya?"

 _Thanks for reading! Sorry I haven't updated much on it's because I have to go through all the chapters and change the entire POV because on Wattpad and Quotev it's X Reader so yeah Cya!_


	9. Chapter Nine

No POV

B: "So do we got a plan or what?"

N: "I know where the .I. building is, I've just never had an interest in it, but since I do now I got an idea... Right so there are typically two Kraang outside the building doors, so I'll take one remove the piece of chewed up gum and bring the rest back so you can fix it up into a suit I can use to get in."

B: "Why do you need the suit? Can't you just walk in?"

N: "Seriously I don't know how many of them could be in there, or what is even in there, so looking like one will make it easier to look around, okay?"

B: " OOOOOh that makes sense."

N: "Yeah, so think you're up to it?"

B: "Yas! This is gonna be fun!"

N: "I'm gonna get going then."

B: "Wait...why do we want to break in again?"

N: *sigh*"Well it might be where I was taken to be experimented on."

B: "And why do we want to go there?"

N: *facepalm* "You're a lost cause, I'm just going to go get the Kraang."

Leonardo POV

I was out patrolling later than usual, I was a bit bored and the other had already gone bad. Having some peace for once is pretty nice, to be honest. I then see what appears to be Nerio carrying a...Kraang suit? while jumping from rooftops.

What on earth is she up to? She doesn't seem to have noticed me so I should probably follow her, see what she's up too.

I follow her for a while until she arrives at an old warehouse in the more rough part of town. She goes over to some kind of scanner at the front doors of the building, the automatically open and close behind her.

This must be her base...

I snoop over to the doors and examine the scanner, it seems to be an eye scanner from what I can tell, but I'm not sure. Well, I'm not getting in that way, maybe there's an old window or something I can see in to see what's going on in there.

I go around the building to find a window or something, this place looks so old I bet I could knock it over myself! There's an old window over here, but it's too dirty to see anything through when I touch it in an attempt to rub some of the dirt off I could swear the whole place looks different for a second, I touch it again keeping my hand on the window this time and it does the same thing. This is pretty weird it must some type of high tech to create an illusion of some old run down warehouse when it is really very highly protected. Donny would be interested in this.

N: "Well, well, well, what do we have here?"

Well, this is just great! (sarcasm)

L: "Nerio."

N: "Yay not that we've shared names what are you doing here?"

L: "Um.."

N: "You know I do have cameras here, you can't possibly expect to waltz over here and expect to go unnoticed, especially with those ninja skills of yours...Well, lack of."

L: "Excuse me-"

N: "Stop talking and just go already."

L: "You're just going to let me go?"

N: "I could kill you where you stand if I wanted to, but I don't."

As if she could kill me just like that- wait what's that? I see a large turret on the roof pointed in my direction. How did I miss that?! It must be retractable or something.

N: "Look I got things to do so if you don't mind leaving before Christmas that would be great. Now hurry up before I change my mind!"


End file.
